Optical disk apparatus and control method thereof

ABSTRACT

An optical disk apparatus and control method having a rotation driver configured to rotationally drive an optical disk, a laser diode configured to emit a laser light to be irradiated upon a recording surface of the optical disk, for recording or reproducing information onto the optical disk, and a monitor device configured to monitor the laser light emitted from the laser diode. An intensity of the laser light emitted from the laser diode which is detected by the monitor device is memorized by a memory, a detector detects an abnormal condition of the laser diode, by comparing a present laser light intensity with a previous laser light intensity, and a controller controls a rotating velocity of the optical disk in dependence upon detection of the abnormal condition.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation application of U.S. application Ser.No. 10/781,711, filed Feb. 20, 2004 now U.S. Pat. No. 7,196,996, thecontents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

The present invention relates to an optical disk apparatus and a controlmethod thereof, for recording information on an optical disk ofrecordable type; such as, a CD-R, a CD-RW, etc., for example, withutilizing a semiconductor laser diode.

Conventionally, in the so-called optical disk apparatus, recording ofinformation is conducted on the optical disk of recordable type, suchas, the CD-R (i.e., the CD-Recordable), a CD-RW (i.e., theCD-ReWritable), and a DVD-RAM (i.e., the Digital Versatile Disc-RandomAccess Memory), for example, with using the laser diode as an opticalsource thereof.

Also, with such the conventional optical disk apparatus, it is possibleto set up a higher linear velocity, to be the linear velocity forperforming the recording; such as, the linear velocity of two (2) times,the linear velocity of four (4) times, the linear velocity of eight (8)times . . . , etc., with respect to the linear velocity when reproducing(this is assumed to be a linear velocity of one (1) time), and then therecording of information is performed at the linear velocity of thathigh speed set up, thereby achieving shortening of the recording time.

Further, as the method for controlling the rotation speed of the opticaldisk, in particular when recording the information, there are alreadyknown the followings: i.e., a CLV (Constant Linear Velocity) controlmethod, for controlling the rotation speed of the optical disk to beconstant in the linear speed at the recording position, i.e., anirradiating portion of a laser light, a CAV (Constant Angular Velocity)method, for controlling the rotating angular velocity of the opticaldisk to be always constant, when recording, and further a control methodof exchanging the CLV method and the CAV method appropriately. Forexample, with the CLV method, the linear velocity when recording is thelinear velocity set up, while with the CAV method, the rotation speed iscontrolled, so that the linear velocity at a recording position, locatedin a radial direction of the optical disk, does no exceed the rotationspeed set up, thereby achieving the record of information.

However, with any of those methods for controlling the rotation speed,an output value of the laser necessary for recording the informationincreases together with an increase of the linear velocity; therefore,in a case where a high linear velocity is set up, a LD (Laser Diode)comes to be unstable in the operation thereof, and there is a problemthat it fails the recording of information.

Then, for example, according to the Patent Document 1 mentioned below,there is already proposed or disclosed an optical disk recordingapparatus, wherein it is possible to operate the LD stable even when thelinear velocity of high speed is set up, thereby enabling to avoid thefailure of recoding information onto the optical disk of the recordabletype.

Japanese Patent Laying-Open No. 2002-324318 (2002); in particular inFIGS. 2 and 3 thereof

Also, such as, a semiconductor laser device and/or a device forcontrolling an output of a laser diode, for example, which can beapplied to a laser printer, a laser scanning apparatus, etc., is alsoalready known, for example, in the following Patent Documents 2 and 3:in which, the laser light emitted by the semiconductor laser is receivedby the means of an inner photodiode or an outer photodiode, so as toobtain the so-called feedback control upon an intensity of lightemission of the laser diode, on the basis of an output of the lightreceived, wherein the current supplied to the laser diode is preventedfrom becoming excessive, thereby preventing the laser diode fromdeterioration thereof.

Japanese Patent Laying-Open No. 2000-206435 (2000); in particular inFIGS. 2 and 3 thereof, and

Japanese Patent Laying-Open No. 2002-16315 (2002); in particular in FIG.3 thereof

With such the conventional technologies as was mentioned above, however,in particular, with such the optical disk recording apparatus and aprogram for controlling the optical disk recoding apparatus, which aredescribed in the former, i.e., the Patent Document 1 mentioned above,wherein while memorizing a maximum value for enabling a stable operationof the laser diode in advance, and there is provided a means forcalculating out an appropriate output value of the laser, responding tothe linear velocity set up, to be compared with that maximum outputvalue memorized in advance, and in a case where it is equal or greaterthan that, it calculates/designates the linear velocity set up to beless than that set-up value thereof. With this, however it is impossibleto detect the deterioration of the laser diode irradiating the lightbeam upon the optical disk when recording information thereon, andtherefore it is also impossible to achieve protection of the laserdiode, as well as, to deal with such the deterioration accompanyingtherewith, in particular, in the recording quality thereof.

On the other hand, with such the semiconductor laser device and/or thecontroller device for controlling an output of the laser diode, beingapplied into the laser scanning apparatus, which are described in thelatter, i.e., the Patent Documents 2 and 3 of the conventional artsmentioned above, when the output of the laser diode is abnormal in thecondition thereof, the laser diode stops the output thereof; thereforewhen applying this into the optical disk apparatus, it is impossible tocontinue the recording operation, and for this reason, there is adrawback that it brings about the deterioration in the recordingquality.

BRIEF SUMMARY OF THE INVENTION

Then, an object is, according to the present invention, by taking thedrawbacks of the conventional arts mentioned above into theconsideration thereof, to provide an optical disk apparatus and acontrolling method thereof, for enabling to deal with the deteriorationof the laser diode, etc., in the optical disk apparatus, and therebyachieving an improvement of the recording quality thereof, as well as,the protection of the laser diode.

Namely, with the laser diode, i.e., a semiconductor element, generally,an intensity of the laser output thereof shows characteristics ofincreasing/decreasing in relation to the drive current (or voltage)thereof. However, due to such the deterioration of the laser diode, orin particular, under the circumferences of being used in hightemperature, a linearity (i.e., a linear relationship) is broken or lostin a region where the output is equal or greater than a certain level,which is established between the drive current and the output of thelaser diode, thereby causing a phenomenon, being so-called a “kink”.Further, such phenomenon is remarkable, in particular, with an opticaldisk apparatus, such as, being so-called a type of super-thin, whereinair circulation is insufficient in an inside thereof accompanying withthe thin-sizing thereof.

Therefore, another object is, according to the present invention, toprovide an optical disk apparatus and a controlling method thereof, forenabling an appropriate execution upon the laser power control and/orthe recording velocity control of the optical disk apparatus, throughdetection of occurring the phenomenon mentioned above, being so-calledthe “kink”, during the recording operation thereof, for the purpose ofdealing with such the deterioration of the laser diode provided in theoptical disk apparatus, thereby achieving an improvement of therecording quality thereof, as well as, the protection of the laserdiode.

In more details, according to the present invention, for accomplishingthose objects mentioned above, first of all, there is provide an opticaldisk apparatus for recording information onto an optical disk,comprising: a laser diode configured to emit a laser light therefrom, tobe irradiated upon a recording surface of the optical disk; a rotationdriver configured to rotationally drive the optical disk; a monitordevice, being position in vicinity of said laser diode, configured tomonitor the laser light emitted from said laser diode; and a controllerconfigured to detect an abnormal condition of said laser diode, throughtime-sequential comparison of an intensity of the laser light emittedfrom said laser diode when the apparatus performs a recording operation,which is detected by said monitor device, and configured to control arotating velocity of the optical disk by said rotation driver, dependingupon detection of said abnormal condition.

And, according to the present invention, also for accomplishing theobject mentioned above, there is provided a control method of an opticaldisk apparatus for recording information onto an optical disk,comprising the following steps of: detecting an abnormal condition of alaser diode, through time-sequential comparison of an intensity of thelaser light emitted from said laser diode when the apparatus performs arecording operation, which is detected by a monitor driver, disposed invicinity of said laser diode, configured to monitor the laser lightemitted from said laser diode; and controlling a rotating velocity ofthe optical disk, depending upon detection of said abnormal condition.

In addition thereto, according to the present invention, in the opticaldisk apparatus or the control method as described in the above, whereinsaid controller may detect the abnormal condition of said laser diode,by using a linear characteristic between driving current or voltage anda light emitting output thereof, or said controller may reduce therotation velocity of the optical disk when detecting said abnormalcondition.

Further, according to the present invention, the optical disk apparatusor the control method as described in the above, preferably, furthercomprises at least a memory configured to memorize an intensity of thelaser light, which is emitted from said laser diode when conducting therecording operation, wherein said controller detects the abnormalcondition of said laser diode, by comparing a present laser lightintensity, which is detected by said monitor device, and a previouslaser light intensity, which is memorized in said memory, or saidcontroller controls said rotation velocity, further by detecting therotation velocity of the optical disk, thereby to determine if saidrotation velocity can be lowered or not thereupon. Or, according to thepresent invention, said controller stops the rotation of said opticaldisk, when determining that said rotation velocity cannot be lowered.And, according to the present invention, the optical disk apparatus asdescribed in the above, said optical disk apparatus is a thin-typehaving a size from 12.7 mm to 9.5 mm in thickness thereof.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

Those and other objects, features and advantages of the presentinvention will become more readily apparent from the following detaileddescription when taken in conjunction with the accompanying drawingswherein:

FIG. 1 is a view for showing the structure of an optical disk apparatus,according to the present invention, mainly around an optical pickupthereof, as to be the feature thereof;

FIG. 2 is a flowchart for showing control operation of the optical diskapparatus mentioned above, according to the present invention;

FIG. 3 is a view for showing an example of an output characteristic of alaser diode, for explaining an “abnormality” in the optical diskapparatus mentioned above, according to the present invention; and

FIG. 4 is a block diagram for showing the entire structure of theoptical disk apparatus, according to one embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, embodiments according to the present invention will befully explained by referring to the attached drawings.

FIG. 4 is the block diagram for showing the entire structure orconfiguration of an optical disk apparatus, according to one embodimentof the present invention. In this figure, upon an optical disk 101 of are-writable recording medium is irradiated a laser beam emitting from anoptical pickup 102. Also, a reflection light being reflected upon theoptical disk 101 is detected by a photo detector of the optical pickup102, and an output generated from the photo detector is converted in tovoltage within an I-V amplifier 104. However, in the present example,the optical pickup 102 is made up with a semiconductor laser (e.g., alaser diode), an optical system, including an objective lens, etc., afocusing actuator, a tracking actuator, a photo detector, and a lensposition sensor, etc., for example.

An output of the I-V amplifier 104 is inputted to an analog signalprocessing circuit 108, and the output of the I-V amplifier 104 iscalculated herein so as to producing a focus error signal, a trackingerror signal and a wobble signal, to be inputted into a focusing andtracking process portion 107, and upon the basis of the focus errorsignal and the tracking error signal, controls are performed on afocusing actuator and a tracking actuator. An RF signal obtained fromthe analog signal processing circuit 108 is equalized in the waveformthereof in an equalizer, and it is digitized in a digitizing circuit117, to be inputted into a PLL circuit 116. In the PLL circuit 116, achannel clock is produced from the digitized signal, and it is inputtedinto a decoder 118. In this recorder 118, the digitized signal isdecoded with an aid of the channel clock, thereby demodulating ordecoding data. Accordingly, reproduced data can be obtained at an outputterminal of the decoder 118.

A reference numeral 109 in the figure depicts a reflection light processportion, for processing the digitized data corresponding to a reflectionlight, which is obtained from the optical disk 101 when conducting testwriting on a test writing area (PCA) of the optical disk 101. An outputof this reflection light process portion 109 is inputted in to a MPU119, and a parameter to be set up into a laser driver 105 is adjustedfinely by means of an output of this MPU 119. Accordingly, with using anoutput of the reflection light process portion 109, it is possible toperform a running OPC (Optimum Power Calibration). A reference numeral112 depicts an asymmetry process portion, which produces a beta (β)value for each recording power from the RF signal outputted from theanalog signal processing circuit 108. Accordingly, by inputting thisdata into the MPU 119, it is possible to determine an optimum powerlevel upon the basis of the β value. Further, within the MPU 119 areconducted; such as, supply of a clock and/or a control signal to eachcircuit, processing of an interruption signal, and control of farm ware(F/W), etc. A reference numeral 114 depicts a wobble process portion,which produces a wobble period or cycle from a wobble signal produced inthe analog signal processing circuit 108. This data is inputted into theMPU 119, and also into a spindle controller circuit 111. The wobblecycle is used in producing of the clock and the spindle control. Also,synch frame timing within a sector can be produced by this wobble cycle.

Record data is modulated (8/16 modulation) in the encoder 115, and isinputted into a recording pulse generator 110. Within the recordingpulse generator 110, NRZI is produced from the modulation data inputtedfrom the encoder 115 and is outputted to a laser control driver 105. Thelaser control driver 105 converts the inputted NRZI signal into a lightemission waveform, thereby controlling the power level of asemiconductor laser (i.e., a laser diode, but not shown in the figure)and pulse width of light emission.

The spindle controller circuit 111 produces a frequency for driving adriver, by the wobble signal inputted form the wobble process portion114 and the signal inputted from a fixed frequency generator of the MPU119. A spindle control driver 106 converts a constant frequency intovoltage, being dependent upon a double-speed, which is inputted from thespindle controller circuit 111 when CAV controlling, thereby driving thespindle motor 103. Also, when CLV controlling, a variable frequencygenerated upon the basis of the wobble signal frequency, which isinputted from the spindle controller circuit 111, is converted intovoltage, thereby to be supplied to the spindle motor 103.

In the decoder 118, the digitized signal is decoded by the channelclock, which is produced in the PLL circuit 116, thereby decoding thedata, and at the same time, the decoder 118 also makes a report to theMPU 119 on whether a correction error is in that decoded data or not, aswell as, of completion of the decoding, for each sector address. Uponthe report from the decoder 118, the MPU 119 memorizes a table in amemory 121, indicative of relationships: such as, between presence ofcorrection error of the data and an error generation frequency, which iscalculated out with using thereof, a read retry number, as well as, anerror generation frequency and the read retry number, which are producedin advance.

Also, normal data decoded in the decoder 118 and data including thecorrection error therein are inputted into a memory controller 122,being attached with address information, and are inputted into a buffermemory 123 upon the basis of control of this memory controller 122. TheMPU 119 can cancel or delete the data including the correction error,which are memorized in the buffer memory 123, by inputting a cancelinstruction to the memory controller 122. Accordingly, in the buffermemory are memorized the normal data, the normal data, which can beobtained through the read retry and are replace by the data includingthe correction error, and the data including the correction error whenthe normal data cannot be obtained through the read retry. The MPU 119can select an outputting method of the data memorized in the buffermemory 123. Upon the basis of an instruction issued from the MPU 119 tothe memory controller 122, the memory controller 122 inputs the datamemorized in the buffer memory 123 into a host interface circuit 124 andan audio DAC 125. As a result of this, a digital data signal isoutputted from the host interface circuit 124, while an analog audiosignal from the audio DAC 125.

Next, in FIG. 1 attached are shown portions relating to the presentinvention, in the optical disk apparatus, the entire structure of whichis explained in the above; in particular, those around the opticalpickup 102 thereof. Namely, within the pickup, there are provided asemiconductor element for outputting a laser light to conduct therecording/reproducing on the optical disk; such as, a laser diode LD,for example, and also, a detector element disposed adjacent thereto, fordetecting an output (an optical intensity) of this laser diode; such as,a front monitor diode (FMD).

A detection signal detected by this front monitor diode (FMD) is, asshown in the figure, inputted to a negative input terminal of acomparator 201, to be compared with a predetermined voltage of a set-upvalue, thereby obtaining feedback control of the driving voltage (orcurrent) to the laser diode LD through the laser driver 202. At the sametime, the detection signal from this front monitor diode FMD is inputtedinto an A/D converter 203 together with an output of the comparator 201mentioned above, thereby being converted into digital signals. Withthis, with the driving voltage of the laser driver 202 when recordingonto the optical disk, a return light level (i.e., an actual intensityof optical output from the laser diode LD) back to the front monitordiode FMD can be monitored. However, though will be mentioned later,this A/D converter 203 memorizes the value of the driving voltage (orcurrent) to the laser diode and the value of the voltage (e.g.,detection signal) of the front monitor diode FMD, which are convertedinto the digital values after obtaining thereof, as was in the above,into a cache memory 204.

On the other hand, a controller portion 205 compares the driving voltageof the laser diode LD from the A/D converter 203 mentioned above and thevoltage of the front monitor diode FMD to the LD driving voltage and theFMD voltage of the previous time, which are memorized within the cachememory 204 mentioned above, thereby determining on whether deteriorationoccurs or not on the laser diode; in particular, on whether aphenomenon, being so-called the kink, occurs or not, where the linearityis lost between the driving voltage and the laser output. As a result ofthis, when it is determined that the phenomenon, being so-called thekink, occurs, the controller portion 205 changes (i.e., lowers) thedriving voltage, so that the laser diode LD can be driven within a powerregion where it can be driven safely much more, through the laser driver202 mentioned above, and it also compares the information of therecordable velocity, which is memorized within the memory 206 inadvance, to the present recording velocity at the present, so as todetermined the optimal rotation velocity where the recording can be madewith an output power (i.e., a low power) of the laser diode LD which ischanged (or lowered) accompanying with change (i.e., lowering) of thedriving voltage, thereby outputting a rotation velocity control signalcorresponding thereto, to the spindle motor 207.

Hereinafter, explanation will be given in more details about the controloperation within the circuit shown in FIG. 1 mentioned above, on whichbrief explanation was given in the above. However, the processes shownin this flowchart is executed, repetitively, for example, at a cycle ofaround one (1) second, by the MPU 119 shown in FIG. 3.

In the processes shown in FIG. 2, first of all, it is checked on thatthe optical disk apparatus is under the recording operation (step S21).Namely, this process is provided to deal with the problem, which iscaused during when the apparatus is recording on the optical disk, aswas mentioned above. Thereafter, upon the basis of an output of the A/Dconverter 203 are detected two (2) values; i.e., the voltage of thefront monitor diode FMD (such as, FMD voltage) and the driving voltageof the laser diode LD (such as, laser driving voltage) (step S22).

Next, comparison is made between those two (2) now-obtained values,which are detected in the above, and the two (2) the before-obtainedvalues, which are detected in advance. Namely, comparison is madebetween the values of the FMD voltage and the laser driving voltage,which are presently detected, to the values of the previous FMD voltageand the laser driving voltage, which are memorized within the cachememory 204 shown in FIG. 1 mentioned above (step S23). However, in thisinstance, if there is no such the before-obtained value about the FDMvoltage and the laser driving voltage, such as in the case when thisprocess is executed at first time, for example, it is determined to be“normal”, and those now-obtained values are memorized in the cachememory 204 mentioned above (step S24). Thereafter, it is confirmed thatthe optical disk apparatus is still continuing the recording operation(step S25), and then it turns back to the step S21 mentioned above.

Herein, explanation will be given about determination of the presence of“abnormality” in the step S23 mentioned above. Normally, the laser diodeshows, so-called, a linear output characteristic, as shown by a solidline “A” in FIG. 3 attached; i.e., increasing the optical output thereofin relation to the laser driving voltage (or current), within the set-updriving range.

However, due to reasons, such as, deterioration of the laser diode, theuse under the condition of high temperature, etc., as is shown by abroken line B and C in FIG. 4, the phenomenon, so-called the kinkoccurs, where the linearity is lost between the laser driving voltage(or current) and the optical output (seethe broken line B). Thus, as wasmentioned in the above, when monitoring the driving voltage of the laserdiode LD and the voltage of the front monitor diode FMD, there sometimesoccurs such a case that the FMD voltage shows a decrease in spite of anincrease of the laser driving voltage, for example. However, such thephenomenon is remarkable, in particular, when the optical disk apparatusis of a super-thin type, being 12.7 mm or 9.5 mm in the thickness, forexample, and as a reason thereof, it can be assumed that an air flow isrestricted within an inside of such the apparatus, accompanying withreduction of the thickness, and therefore, the temperature comes upeasily, in particular, in a periphery of the laser diode, as the heatgeneration source.

According to the present embodiment, when occurring such the phenomenon,it is determined that the “abnormality” exists in the diode, therebytrying to protect the laser diode therefrom, by lowering down thedriving range, in particular, an upper limit in a high output region.Also, at the same time to that, also the rotating velocity (i.e.,recording speed) of the optical disk is lowered during when recording,in the operation, accompanying with the decrease of the optical outputfrom the laser diode, so as to enable the execution of the recordingoperation onto the optical disk even if the laser diode is low in thepower thereof, thereby improving the recording quality.

Then, in more details, in the step S 23 mentioned above, the values ofthe now-detected FMD voltage and the laser driving voltage are comparedto those of the previous FMD voltage and the laser driving voltage, soas to determine on whether the kink phenomenon occurs or not, loosingthe linearity between the laser driving voltage and the optical output,or the deterioration occurs or not in the output characteristics, due tothe use thereof under the condition of high temperature, with respect tothe laser diode under the condition of the recording operation.

Further, when making the determination in the step S23 mentioned above,it is also possible to calculate out a ratio R between the change of thelaser driving voltage Vdr and that of the optical output Pout by theflowing equation, for example, thereby to determine the presence of the“abnormality” upon if this ratio stays within a predetermined region ornot.R=(Pn−Pn−1)/(Vn−Vn−1)  (Eq. 1)Rlow≦R≦Rup  (Eq. 2)

Herein, “Rlow” indicates the lower limit value of the predeterminedregion mentioned above, while “Rup” the upper limit value thereof.However, according to the present embodiment, the method should not berestricted only to that mentioned above, and it is also possible tomemorize, not only the now-detected values and the before-detectedvalues, but also the values which are detected further before, therebydetecting the deterioration of the output characteristics due to, suchas, the kink phenomenon and/or the use under the condition of hightemperature, according to the comparison therewith. Or, in a case whenthe laser driving voltage Vdr does not change, it is possible todetermine the presence of the “abnormality” by making comparison only onthe change of the optical output Pout to the previous value, so as todetermine that the change stays within a predetermined region or not.Furthermore, in such the instance, while detecting the temperaturewithin the apparatus (in particular, within an inside of the pickup), itis also possible to bring the upper and the lower limit values of thepredetermined region or the predetermined region itself to be variabledepending upon the temperature detected.

And, in a case where it is determined to be “abnormal” in the step S23mentioned above, the recording velocity is determined at that time (stepS26). With this, comparison is made between the recordable velocity,which is memorized within the memory (for example, being defined by F/Wwithin the drive) and the recording velocity which is set up at present,thereby determining on whether a deceleration can be made or not ontothe recording velocity. In more details, the velocity which is set up atpresent is coincident with the lowest one of the recordable velocities,since it is impossible to reduce the recording velocity much lower,therefore it is determined to be “impossible to decelerate”, but on theother hand, in the other cases, it is determine to be “possible todecelerate”.

Thereafter, in a case where it is determined to be “impossible todecelerate” in the step S26 mentioned above, an enable signal outputtedfrom the controller portion mentioned above is set to be OFF, todistinguish the laser diode, thereby stopping the recording operation(step S27), and then the process is ended. However, herein the enablesignal is a signal for selecting an input to be valid/invalid to thelaser driver mentioned above. Namely, even if the voltage is set-up forlaser light emission of the laser diode from the laser driver, the laserdiode does not emit the light if it is invalidated by setting up thisenable signal into OFF.

On the other hand, if it is determined to be “possible to decelerate” inthe step S26 mentioned above, the controller portion controls thespindle motor, to decelerate the recording velocity down to a speedlower than that by one step (step S28), and thereafter, it turns back tothe step S22 mentioned above. With this, the laser driver is able toreduce the optical output thereof, due to the fact that the recordingvelocity is decelerated. Namely, with the driving voltage within theregion where neither such the kink phenomenon nor the deterioration inthe output characteristics occurs, it is possible to bring the laserdiode to emit the light safely, as well as, to obtain the recordingoperation of high quality.

Also, according to the present invention, the explanation was given onthe assumption that deceleration of the recording velocity is made downto the velocity lower than that by one step in the above, howeveraccording to the present invention, it should not be restricted only tothat. For example, in a case of a control method of exchanging the CLVmethod and the CAV method, appropriately, it is needless to say that thedeceleration can be made on the recording velocity, such as, exchangingfrom the CAV (i.e., an angular velocity) to the CLV (i.e., a linearvelocity) control, for example.

The present invention may be embodied in other specific forms withoutdeparting from the spirit or essential feature or characteristicsthereof. The present embodiment(s) is/are therefore to be considered inall respects as illustrative and not restrictive, the scope of theinvention being indicated by the appended claims rather than by theforgoing description and range of equivalency of the claims aretherefore to be embraces therein.

As was fully described in the above, with the optical disk apparatus andthe control method of the optical disk apparatus, according to thepresent invention, it is possible to deal with the deterioration of thelaser diode, or the like, in the super or ultra-thin type, such as,having a size from 12.7 mm to 9.5 mm in thickness thereof, for example,and also to obtain an improvement on the recording quality thereof, aswell as, obtaining the protection of the laser diode, thereby achievingsuperior effects.

1. An optical disk apparatus having a rotation driver configured torotationally drive an optical disk, a laser diode configured to emit alaser light to be irradiated upon a recording surface of the opticaldisk, for recording or reproducing information onto the optical disk,and a monitor device configured to monitor the laser light emitted fromthe laser diode, comprising: a memory configured to memorize anintensity of the laser light emitted from the laser diode which isdetected by the monitor device; a detector configured to detect anabnormal condition of the laser diode, by comparing a present laserlight intensity detected by the monitor device with a previous laserlight intensity memorized in the memory; and a controller configured tocontrol a rotating velocity of the optical disk by the rotation driverin dependence upon detection of the abnormal condition.
 2. The opticaldisk apparatus according to claim 1, further comprising a temperaturedetector configured to detect a temperature in the optical diskapparatus; wherein the intensity of the laser light is memorized in thememory as a permissible range of intensity of the laser light; whereinthe permissible range of intensity of the laser light is changed basedon the temperature detected by the temperature detector; and wherein thedetector detects the abnormal condition of the laser diode by comparinga present laser light intensity with the permissible range of intensityof the laser light.
 3. An optical disk apparatus having a rotationdriver configured to rotationally drive an optical disk, a laser diodeconfigured to emit a laser light to be irradiated upon a recordingsurface of the optical disk, for recording or reproducing informationonto the optical disk, a laser driver configured to provide drivingcurrent or voltage to the laser diode, and a monitor device configuredto monitor the laser light emitted from the laser diode, comprising: amemory configured to memorize a linear characteristic provided bycalculating the driving current or voltage to the laser diode which isprovided by the laser driver and an intensity of the laser light emittedfrom the laser diode which is detected by the monitor device; a detectorconfigured to detect an abnormal condition of the laser diode, bycomparing a present linear characteristic detected by the monitor devicewith a previous linear characteristic memorized in the memory; and acontroller configured to control a rotating velocity of the optical diskby the rotation driver in dependence upon detection of the abnormalcondition.
 4. The optical disk apparatus according to claim 3, furthercomprising a temperature detector configured to detect a temperature inthe optical disk apparatus; wherein a permissible range of the linearcharacteristic memorized is changed based on the temperature detected bythe temperature detector; and wherein the detector detects the abnormalcondition of the laser diode by comparing a present linearcharacteristic with the permissible range of the linear characteristic.5. A control method of an optical disk apparatus having a rotationdriver configured to rotationally drive an optical disk, a laser diodeconfigured to emit a laser light to be irradiated upon a recordingsurface of the optical disk, for recording or reproducing informationonto the optical disk, and a monitor device configured to monitor thelaser light emitted from the laser diode, comprising the steps of:memorizing to a memory an intensity of the laser light emitted from thelaser diode which is detected by the monitor device; detecting anabnormal condition of the laser diode by comparing a present laser lightintensity detected by the monitor device with a previous laser lightintensity memorized in the memory; and controlling a rotating velocityof the optical disk by the rotation driver in dependence upon detectionof the abnormal condition.
 6. The control method of an optical diskapparatus according to claim 5, further comprising the step of detectinga temperature in the optical disk apparatus; wherein the intensity ofthe laser light is memorized in the memory as a permissible range ofintensity of the laser light; wherein the permissible range of intensityof the laser light is changed based on the temperature detected in thedetecting step; and wherein said the abnormal condition of the laserdiode is detected in the detecting step by comparing a present laserlight intensity with the permissible range of intensity of the laserlight.
 7. A control method of an optical disk apparatus having arotation driver configured to rotationally drive an optical disk, alaser diode configured to emit a laser light to be irradiated upon arecording surface of the optical disk, for recording or reproducinginformation onto the optical disk, a laser driver configured to providedriving current or voltage to the laser diode, and a monitor deviceconfigured to monitor the laser light emitted from the laser diode,comprising the steps of: memorizing to a memory a linear characteristicprovided by calculating the driving current or voltage to the laserdiode provided by the laser driver and an intensity of the laser lightemitted from the laser diode which is detected by the monitor device;detecting an abnormal condition of the laser diode by comparing apresent linear characteristic detected by the monitor device with aprevious linear characteristic memorized in the memory; and controllinga rotating velocity of the optical disk by the rotation driver independence upon detection of the abnormal condition.
 8. The controlmethod of an optical disk apparatus as described in the claim 7, furthercomprising the step of detecting a temperature in the optical diskapparatus; wherein a permissible range of the linear characteristicmemorized is changed based on the temperature detected in the detectingstep; and wherein the abnormal condition of the laser diode is detectedin the detecting step by comparing a present linear characteristic withthe permissible range of the linear characteristic.